Download zipped release file here, 

https://github.com/yui/yui3
https://github.com/yui/yui3/archive/master.zip

Unzip,

# unzip release-3.17.2,zip

Install skin assets into build directory by copyiung from src,

# cp -r yui3-release-3.17.2/src/common/assets yui3-release-3.17.2/build 

Create combo-loader config file and symlink to install directory.

# vim yui3-release-3.17.2-applyconfig.js
...

# ln -s ../yui3-release-3.17.2-applyconfig.js yui3-release-3.17.2/yui3-applyconfig.js